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If you were along the Bay Area coastline Thursday, you probably noticed that the water levels were extremely high. Cheryl Hurd explains why. (Published Thursday, Dec. 13, 2012)

Extremely high tides rolled into the Bay Area's coastal cities on Thursday, and flooding was reported along the Embarcadero in San Francisco and Lucky Drive in Marin.

People walking along the Sausalito waterway in Marin County said they had not seen the water this high in decades.

High Tides Flood Bay Area Thursday

Why the floods if it wasn't raining out?

The swells are caused by a semi-regular astronomical event called "king tide." King tides come between two and four times a year when the gravitational forces of the sun, the Earth and a full moon are all in alignment. This king tide episode should ease off by Friday.

Until then, the tide levels are expected to range from a couple inches to several feet higher than normal. Experts said the highest estimated tide level is 10.5 feet, which is expected at San Jose's Coyote Creek.

The group that named the tides, "king tides," says what happens this week gives us a glimpse of what the state can expect as sea level rises in the coming years. The California King Tides Initiative cites a report released earlier this year by the National Academy of Sciences, which projects a one- foot, sea level rise by 2050 and up to five feet by 2100 along the California coast.

"One of the important things to think about is that today's high tide of the year could become a daily occurrence," Heidi Nutters of the San Francisco Bay National Estuarine Research Reserve said.

The tides are hitting the entire state of California. Television and radio reports say Huntington Harbour overflowed onto Pacific Coast Highway in Sunset Beach, starting around 8 a.m. Thursday. Similar flooding was seen along the bayfront properties in Newport Beach. The nearby city of Seal Beach reported no immediate flooding, but police say the city already had erected its winter storm berm on the south side of the pier and also made sure that its pumps were working and its drains clear.

The next king tides should occur between Jan. 9 and 11, and then again between Feb. 7 to 9.